Schwannoma of the gastrointestinal tract: a clinicopathological, immunohistochemical and ultrastructural study of 33 cases

FDG PET/CT in a Case of Esophageal Schwannoma

ABSTRACT

Esophageal schwannoma is very rare. We describe FDG PET/CT findings in a case of benign esophageal schwannoma. Endoscopic ultrasound showed the tumor was located in the muscular layer of the esophagus. FDG PET/CT showed intense FDG uptake with SUV max of 10 of the tumor mimicking malignancy. This case indicates that schwannoma should be included in the differential diagnosis of esophageal FDG-avid lesions.

A rare case of schwannoma of the small intestine discovered during intussusception

A woman in her 60s with anemia was diagnosed with a small intestinal intussusception on computed tomography. She underwent a double-balloon endoscopy, which revealed submucosal tumor in the ileum. Suspected to be the cause of anemia and intussusception, surgical intervention was carried out, revealing it to be a schwannoma. Schwannomas of the small intestine are very rare, and because exophytic growths are common, intussusception due to luminal side development is even rarer.

Systematic Characterization of the Clinical and Pathological Features of Schwannomas Harboring SH3PXD2A::HTRA1 Fusion

The understanding of schwannoma tumorigenesis has been reshaped by the recent identification of SH3PXD2A::HTRA1 fusion in 10% of intracranial/spinal schwannomas. Nonetheless, pathologic features of schwannomas harboring this fusion, as well as its prevalence outside intracranial/spinal locations, have not been characterized. We screened 215 consecutive schwannomas for their clinicopathologic characteristics and fusion status using reverse-transcriptase polymerase chain reaction (RT-PCR). Among 29 (13.5%) fusion-positive schwannomas, the most prevalent location was peripheral somatic tissue (30.7%, 19/62), followed by spinal/paraspinal (18.4%, 7/38), body cavity/deep structures (10%, 2/20), intracranial (1.3%, 1/75), and viscera (0/13). All 8 cellular, 4 microcystic/reticular, and 3 epithelioid schwannomas were fusion-negative, as were 41/42 nonschwannomatous peripheral nerve sheath tumors. Remarkably, a distinct 'serpentine' palisading pattern, comprising ovoid/plump cells shorter than usual schwannian cells in a hyalinized stroma, was identified in most fusion-positive cases and the schwannomatous component of the only fusion-positive malignant peripheral nerve sheath tumor. To validate this finding, 60 additional cases were collected, including 36 with (≥10% arbitrarily) and 24 without appreciable serpentine histology, of which 29 (80.6%) and 2 (8.3%) harbored the fusion, respectively. With percentages of 'serpentine' areas scored, 10% was determined as the optimal practical cut-off to predict the fusion status (sensitivity, 0.950; specificity, 0.943). Fusion positivity was significantly associated with serpentine histology, smaller tumors, younger patients, and peripheral somatic tissue, while multivariate logistic linear regression analysis only identified serpentine histology and location as independent fusion-predicting factors. RNA in situ hybridization successfully detected the fusion junction, highly concordant with RT-PCR results. Gene expression profiling on 18 schwannomas demonstrated segregation largely consistent with fusion status. Fusion-positive cases expressed significantly higher HTRA1 mRNA abundance, perhaps exploitable as a biomarker. In summary, we systematically characterize a series of 60 SH3PXD2A::HTRA1 fusion-positive schwannomas, showing their distinctive morphology and location-specific prevalence for the first time.

Gastric Schwannoma: A Rare Subepithelial Lesion of the Stomach

Gastric schwannomas (GS) are rare, slow-growing, benign subepithelial (SE) lesions of the stomach. These are difficult to differentiate preoperatively from other types of SE lesions, as the gross appearance and clinical presentation are very similar especially the gastrointestinal stromal tumors (GISTs), which are the most common SE lesions of the stomach. We present the case of a 35-year-old Asian man with a one-month history of intermittent, right, upper quadrant pain and hematemesis. Preoperatively, intravenous contrast-enhanced computer tomography scan (CECT) showed a well-circumscribed lesion in the upper abdomen closer to the stomach's lesser curvature. Endoscopic ultrasound revealed an ulcerated subepithelial lesion and subsequent biopsy with a 22-gauge fine-needle biopsy (22G FNB) needle confirmed the diagnosis of GS. The patient underwent distal gastrectomy and a Bilroth 1 procedure. The postoperative biopsy was consistent with the initial one, therefore supporting the diagnosis of gastric schwannoma. Postoperatively, the recovery remained uneventful.

Clinicopathological characteristics of gastrointestinal schwannomas: A retrospective analysis of 78 cases

Introduction

Schwannomas are tumors arising from Schwan cells of the neural sheath, which rarely occur in the gastrointestinal tract. The aim of the present study was to analyze the clinicopathological features and treatment outcomes of gastrointestinal schwannomas (GISs).

Methods

Patients who were diagnosed with GISs in our hospital from January 2010 to December 2021 were selected. Data about demographic characteristics, clinical symptoms, treatment methods and outcomes, pathological results, and follow-up results were retrospectively collected and analyzed.

Results

A total of 78 patients with 79 GISs were included, the female-to-male ratio was 55:23, and the average age was 52.12 ± 12.26 years. One-third (26/78) of the patients were asymptomatic. A total of 79 GISs were removed, and the average size was 3.63 ± 2.03 cm (range, 0.3-10 cm). As for tumor location, 54 GISs were located in the stomach, 14 in the esophagus, 2 in the duodenum, 6 in the colorectum (4 in the colon and 2 in the rectum), and the other 3 in the small intestine. A total of 23 and 55 patients underwent endoscopic and surgical resections, respectively. Compared with surgical resection, endoscopic resection is associated with a smaller diameter, lower cost, and shorter hospital stay. Pathological results revealed that S100 was positive in all the GISs. No recurrence was noticed during a median follow-up of 45 months (range, 6-148 months).

Conclusion

GISs are rare gastrointestinal tumors with favorable prognoses, which are most commonly seen in the stomach and diagnosed by pathological findings with immunohistochemical staining. Surgical resection remains the standard method for removing GISs, while endoscopic resection may serve as an alternative method for selected patients with GISs and may be attempted in GISs with a diameter of <3 cm and no signs of malignancy.

Schwannoma of the Ascending Colon in a 22-Year-Old Male: A Case Report

Schwannoma of the ascending colon is an extremely rare neoplasm that is often discovered incidentally in the asymptomatic older population on surveillance colonoscopy. We present the case of a symptomatic 22-year-old male presenting with one month of discomfort in the right lower abdominal quadrant, abdominal bloating, and hematochezia. A sessile polyp measuring 0.5 cm was identified in the ascending colon on the colonoscopy. The polyp was completely resected using cold snare polypectomy. Histological examination of the resected polyp with hematoxylin-eosin staining revealed small nodules of bland spindle cells with focal nuclear condensation. The lesional cells tested positive for S-100 and SOX-10 on immunohistochemical analysis, establishing the diagnosis of benign schwannoma. Since this lesion was submucosal, its diagnosis required an endoscopic biopsy that could only be performed on the mucosa. It was difficult to distinguish it from other mesenchymal tumors (gastrointestinal stromal tumor or leiomyoma), and this makes the differential diagnosis exceedingly challenging. If the immunohistochemistry is positive for S-100 and negative for C-KIT, CD-34, actin, and desmin, it aids in diagnosis. These tumors have non-specific radiological features and are asymptomatic.

Esophageal Schwannoma: An Important Differential Diagnosis for Esophageal Subepithelial Lesions

Esophageal schwannoma is a rare tumor and is classified as one of the esophageal subepithelial lesions (SELs). Endoscopic ultrasound (EUS) evaluation is the gold standard for evaluating subepithelial lesions. Differentiation through EUS-guided fine needle aspiration is sometimes important to exclude lesions with malignant potential. Immunohistochemistry differentiates schwannoma from other subepithelial lesions. Strong and diffuse positivity for S100 is characteristic. The decision for conservative management versus endoscopic or thoracoscopic intervention is made based on the tumor size, location, and symptoms.

Colonic schwannoma: A case of unusual presentation and outcome

Background: Schwannomas are mesenchymal tumors arising from neural sheath cells and whose diagnosis is based on immunohistochemistery. The digestive and especially colonic location of this tumor is rare. Commonly described in elderly patient, their malignancy is unusual. Case report: We report the case of a 23-year-old girl, with learning disability, operated in emergency for acute peritonitis. Peroperatively, we discovered a peritonitis secondary to a bulky perforated cecal tumor. We performed a right colectomy and an ileostomy. The posterior margin of the resection was macroscopically involved. The diagnosis of colonic schwannoma was confirmed with immunopathological examination of the surgical specimen. Surgical exploration 4 months later and morphological investigations during 2 years showed stability of the tumoral residue in the right iliac fossa. However, we noticed, on CT scanning control 2 years postoperatively, the appearance of a mesenteric recurrence. Exploratory laparotomy confirmed the unresectability of this mesenteric mass and showed the presence of multiple parietal nodules whose biopsies revealed their neurofibromatous nature. The 4 year follow-up of the patient didn’t reveal any complication rather than need to right nephrostomy due to ureter compression by the primary tumoral residue. Discussion: Colonic schwannoma is a rare disease, commonly described in uncomplicated stages. The learning disability of our patient had favorized the absence of declared symptoms and promoted the evolution of the cecal swhannoma until its perforation. This complication was not described before. Local recurrence has been also rarely reported in the literature. Association with neurofibroma may be hereditary in a context of neurofibromatosis or sporadic. Conclusion: Colonic schwannoma may have polymorphic presentation mimicking malignant tumor in such cases. Not treated in time, it can lead to severe complications, such as tumoral perforation. Surgical resection remains the mainstay treatment. The slow evolutionary genius of schwannoma, even when incompletely resected by necessity, confirms its good prognosis.

Natural history of gastrointestinal schwannomas

Background and study aims  Data are lacking on the natural history of gastrointestinal tract schwannomas. We aimed to study the natural history of all gastrointestinal schwannomas including location, diagnosis, management, and long-term outcomes. Patients and methods  Patients with a pathological diagnosis of gastrointestinal schwannoma between January 2000 and March 2020 were identified. Data on baseline demographics, presentations, associated malignancies, malignant transformation, treatment, and recurrence were collected. Results  Our cohort consisted of 44 patients with a mean age of 58.6 years, with 63.6 % women and 84.1 % White. The stomach (38.6 %) was the most common location followed by the colorectum (31.8 %). Only 22.7 % of patients were symptomatic and 22.0 % had a personal history of other malignancies. Tissue diagnosis was obtained via endoscopy in 47.7 % and from surgical pathology in 52.3 %. On histology, 65.9 % of the tumors were solid, 11.4 % had mixed features, and 2.3 % had necrosis. SP100 was tested in all but one patient and was positive in all. Mean Ki-67 in 12 patients with tumors measuring ≥ 2 cm was 3.0 % indicating a low proliferation rate. Of the patients, 77.3 % had surgery and 18.2 % underwent endoscopic resection. At a mean follow-up of 5.0 ± 4.31 years, there was no malignant transformation, recurrence or mortality associated with gastrointestinal schwannomas. Conclusions  Gastrointestinal schwannomas are diagnosed in the fifth to sixth decade with predominance in women and Whites. They are benign, mostly asymptomatic, and diagnosed incidentally. Asymptomatic gastrointestinal schwannomas including lesions ≥ 2 cm in size do not appear to need further monitoring or intervention. Patients with them should be counseled to remain up to date with routine screening guidelines pertaining to the colon, breast, and lung cancer due to the high incidence of concomitant malignancy.

Laparoscopic-assisted endoscopic full-thickness resection of a large gastric schwannoma: A case report

BACKGROUND

Schwannomas, also known as neurinomas, are benign tumors derived from Schwann cells. Gastrointestinal schwannomas are rare and are most frequently reported in the stomach. They are usually asymptomatic and are difficult to diagnose preoperatively; however, endoscopy and imaging modalities can provide beneficial preliminary diagnostic data. There are various surgical options for management. Here, we present a case of a large gastric schwannoma (GS) managed by combined laparoscopic and endoscopic surgery.

CASE SUMMARY

A 28-year-old woman presented with a 2-mo history of epigastric discomfort and a feeling of abdominal fullness. On upper gastrointestinal endoscopy and endoscopic ultrasonography, a hypoechogenic submucosal mass was detected in the gastric antrum: It emerged from the muscularis propria and projected intraluminally. Computed tomography showed a nodular lesion (4 cm × 3.5 cm), which exhibited uniform enhancement, on the gastric antrum wall. Based on these findings, a preliminary diagnosis of gastrointestinal stromal tumor was established, with schwannoma as a differential. Considering the large tumor size, we planned to perform endoscopic resection and to convert to laparoscopic treatment, if necessary. Eventually, the patient underwent combined laparoscopic and gastroscopic surgery. Immunohistochemically, the resected specimen showed positivity for S-100 and negativity for desmin, DOG-1, α-smooth muscle actin, CD34, CD117, and p53. The Ki-67 index was 3%, and a final diagnosis of GS was established.

CONCLUSION

Combined laparoscopic and endoscopic surgery is a minimally invasive and effective treatment option for large GSs.

Adrenal schwannoma: why should endocrinologists be aware of this uncommon tumour?

PURPOSE

Adrenal schwannomas (AS) are rare tumours arising from Schwann cells. Due to the high prevalence of adrenal incidentalomas, running into very rare adrenal tumours has become a possibility for high volume expert centres. So far, the clinical behaviour and the radiological characteristics of AS make the pre-operative diagnosis of AS extremely challenging. Due to limited information available, we wanted to summarise the main features of this tumours, in order to raise the profile of an uncommon disease.

METHODS

We performed a MEDLINE and EMBASE research to review the literature. We found 57 case reports and case series and a total of 169 cases, including 2 more cases found in our Institutions. We collected data regarding year of publication, sex, age, and, when available, clinical presentation, hormonal data, radiological features, tumour site and size, treatment, histology and follow-up.

RESULTS

We analysed and discussed the clinical, radiological and pathological characteristics of cases identified, underlying the critical aspects of assessment and management of these tumours which still remain questioned, as, currently, pathologic examination is the only way to make the diagnosis.

CONCLUSIONS

The pre-operative diagnosis of AS is more than challenging and pathologic examination is so far the only way to make a certain diagnosis. Therefore, it is important to consider also the AS in the list of possible diagnoses when faced with a large not secreting adrenal tumour, with suspicious radiological features.

Gastric schwannoma treated by endoscopic full-thickness resection and endoscopic purse-string suture: A case report

BACKGROUND

Schwannomas, also known as neurinomas, are tumors that derive from Schwann cells. Gastrointestinal schwannomas are extremely rare, but the stomach is the most common site. Gastric schwannomas are usually asymptomatic. Endoscopy and imaging modalities might offer useful preliminary diagnostic information. However, to diagnose schwannoma, the immunohistochemical positivity for S-100 protein is essential, whereas CD117, CD34, SMA, desmin, and DOG-1 are negative.

CASE SUMMARY

A 45-year-old female was found to have a gastric mass during a medical examination, which was diagnosed as a gastric schwannoma. We performed endoscopic full-thickness resection and endoscopic purse-string suture. Pathology and immunohistochemical staining confirmed the diagnosis of gastric schwannoma through the positivity of S-100 protein. Furthermore, to exclude the misdiagnosis of gastrointestinal stromal tumor, we performed a mutational detection of the c-Kit and PDGFRA genes. Postoperative follow-up revealed that the patient recovered well.

CONCLUSION

Immunohistochemical staining is essential for the diagnosis of schwannoma. Endoscopic full-thickness resection is an effective treatment method for gastric schwannoma.

PET/CT and contrast-enhanced CT imaging findings in benign solitary schwannomas

OBJECTIVES

Imaging features of positron emission tomography (PET)/computed tomography (CT) and contrast-enhanced CT and pathological changes in benign solitary schwannoma were retrospectively analyzed, and the factors associated with high uptake of fluorodeoxyglucose (FDG) were examined.

METHODS

The PET/CT, contrast-enhanced CT, and pathological results of 58 cases of benign solitary schwannomas confirmed by surgery or biopsy were retrospectively analyzed. The association of each variable with the maximum standardized uptake value (SUVmax) was evaluated.

RESULTS

The SUVmax of the 58 benign schwannoma cases was 4.1 ± 2.1 (1.5-11.1). When the locations of schwannomas were divided into gastrointestinal system/heart/abdominal and pelvic cavities/thoracic wall (type-1 locations) and other sites (type-2 locations), the schwannoma location was significantly correlated with the SUVmax (r = 0.538, p =  0.000). The SUVmax values were 5.8 ± 2.4 and 3.3 ± 1.5, respectively (p =  0.000). Peritumoral lymphoid cuffs were observed in 7 cases, 4 of which were tumors of gastrointestinal origin, accounting for 80 % of the gastrointestinal schwannomas (4/5). The presence of peritumoral lymphoid cuffs was significantly correlated with the SUVmax (r = 0.456, p =  0.000). The location of the schwannoma was significantly correlated with the presence of peritumoral lymphoid cuffs (r = 0.640, p =  0.000). We found that a peritumoral lymphoid cuff is strongly correlated with the presence of regional lymphadenopathy. Among the 7 cases showing peritumoral lymphoid cuffs, 5 cases had the presence of peritumoral enlarged lymph nodes. The degree of enhancement was significantly correlated with the SUVmax (r = 0.556, p =  0.000).

CONCLUSIONS

Benign schwannomas originating from the gastrointestinal system/heart/abdominal location and showing the presence of peritumoral lymphoid cuffs or moderate and significant enhancement on contrast-enhanced CT were significantly associated with high FDG uptake. An accurate understanding of the factors associated with high FDG uptake can help reduce the misdiagnosis rate.

Perilesional Lymph Node Swelling Might Be a Radiologic Clue for Appendiceal Schwannoma: A Case Report

BACKGROUND

Gastrointestinal schwannoma is not a common type of tumor, and lesions originating from the appendix are extremely rare. Herein, we report a patient with appendiceal schwannoma characterized by lymph node swelling.

CASE REPORT

A 67-year-old male patient who had diabetes complained of weight loss. A computed tomography scan revealed a mass in the right side of the pelvic cavity. Moreover, a contrast-enhanced computed tomography scan showed perilesional lymph node swelling measuring up to 28 mm. A low-intensity mass was observed on T1-weighted imaging, heterogeneous high-intensity mass on T2-weighted imaging, and restricted diffusion on diffusion-weighted imaging. There were no abnormal findings on colonoscopy. Based on a preoperative examination, a differential diagnosis of either appendiceal schwannoma, carcinoid, or gastrointestinal stromal tumor was considered. During surgery, a large appendiceal mass and multiple swollen perilesional lymph nodes were observed. Therefore, ileocecal resection and D3 lymph node dissection were performed. Pathological and immunohistochemical analyses confirmed the diagnosis of appendiceal schwannoma. There were numerous swollen lymph nodes in the mesenteric region. The lymph nodes revealed reactive lymphoid hyperplasia, with enlarged follicles of various sizes and shapes with an irregular distribution. Almost all lymphocytes, except those at the germinal centers, were small.

CONCLUSION

Gastrointestinal schwannoma is characterized by lymph node swelling. Appendiceal schwannoma may have characteristics, including peritumoral lymph node swelling, similar to other types of gastrointestinal schwannoma such as that in the stomach. Thus, this characteristic can be a diagnostic clue for appendiceal schwannoma.

Mesenchymal tumours of the gastrointestinal tract

Mesenchymal tumours represent a heterogenous group of neoplasms encopassing benign, intermediate malignancy, and malignant entities. Sarcomas account for approximately 1% of human malignancies. In consideration of their rarity as well as of intrinsic complexity, diagnostic accuracy represents a major challenge. Traditionally, mesenchymal tumours are regarded as lesions the occurrence of which is mostly limited to somatic soft tissues. However, the occurrence of soft tissue tumours at visceral sites represent a well recognized event, and the GI-tract ranks among the most frequently involved visceral location. There exist entities such as gastrointestinal stromal tumours (GIST) and malignant gastointestinal neuroectodermal tumors that exhibit exquisite tropism for the GI-tract. This review will focus also on other relevant clinico-pathologic entities in which occurrence at visceral location is not at all negligible.

Gastric schwannoma: a case report and literature review

BACKGROUND

Gastric schwannoma is a rarely seen gastric tumor accounting for only 0.2% of all gastric tumors. It is difficult to distinguish a gastric schwannoma from other gastric tumors preoperatively.Case presentation: A 30-year-old man with no significant medical history or physical examination findings presented with a 1-month history of right upper abdominal discomfort. The preoperative diagnosis was a gastrointestinal stromal tumor, but the postoperative pathologic and immunohistochemical examinations confirmed a gastric schwannoma. The patient underwent laparoscopic wedge resection of the stomach without additional postoperative treatment, and his postoperative recovery was uneventful. No recurrence or metastasis was found at the 2-year follow-up examination.

CONCLUSION

Although gastric schwannomas are usually not malignant, they are difficult to distinguish from other malignant stromal tumors preoperatively. Surgical resection should be recommended when a schwannoma is malignant or considered to be at risk of becoming malignant.

Current status of the diagnosis and treatment of gastrointestinal schwannoma

Gastrointestinal schwannoma is a rare, slow-growing and benign tumor that mostly originates in the Auerbach myenteric nerve plexus in the gastrointestinal tract. The clinical manifestations may be associated with the location, size, differentiation type, and degree of malignancy of the tumor. Endoscopy, ultrasound and imaging examinations serve an important auxiliary role in the clinical identification, diagnosis and differential diagnosis of lesions; assessment of risk; and preparation for surgery. S-100 positivity is a hallmark of schwannoma. CD34, CD117, discovered on GIST-1, P53, ALK, β-catenin, smooth muscle actin and Desmin negativity are helpful for the identification of other gastrointestinal stromal tumors. Surgical removal of the tumor is the main treatment for schwannoma. Benign gastrointestinal schwannoma has a good prognosis without recurrence and metastasis; malignant transformation is extremely rare and has a poor prognosis.

Occult follicular lymphoma in a swollen regional lymph node of gastric schwannoma

BACKGROUND

Regional lymphadenopathy is more commonly noted in gastric schwannomas than in other gastric submucosal tumors. Most of the swollen lymph nodes associated with gastric schwannomas are non-metastatic lymphadenopathy.

CASE PRESENTATION

A 69-year-old Japanese woman was referred to our hospital with a chief complaint of abdominal discomfort. Contrast-enhanced computed tomography (CT) of the abdomen revealed an extraluminal tumor with heterogeneous enhancement at the middle stomach on the lesser curve, accompanied with one swollen lymph node approximately 10 mm in size and several small lymph nodes in the perigastric region. These lymph nodes were flat; therefore, we considered them to be non-metastatic. The main tumor was removed via wedge resection. Soft and slightly swollen lymph nodes, which were compatible with the lymph nodes noted in the preoperative CT, were found near the main tumor in the fatty tissue at the lesser curvature of the stomach. An excisional biopsy of the largest lymph node was performed for the diagnosis. Based on pathological findings, a diagnosis of gastric schwannoma and follicular lymphoma (FL) was confirmed. The patient is doing well without recurrence of either the gastric schwannoma or FL 28 months postsurgery.

CONCLUSIONS

The present report detailed an extremely rare case of FL coincidentally discovered in the swollen regional lymph node of gastric schwannoma.

Periampullary duodenal schwannoma mimicking ampullary neoplasm

Schwannomas are neurogenic tumors that arise from Schwann cells in the neural sheath. Gastrointestinal schwannomas occur most often in the stomach, followed by the colon and the rectum. Duodenal schwannomas are rare amongst mesenchymal tumors of the gastrointestinal tract and only a few cases have been reported up to the current date with an incidence of approximately 2%-6%. Duodenal Schwannomas do not have characteristic imaging features thereby cannot be easily differentiated from other submucosal and adjacent extraluminal neoplasms. We present a case of a 76-year old male patient that presented to our hospital with abdominal pain and was diagnosed after an upper gastrointestinal endoscopy with an ampullary duodenal neoplasm that proved to be a periampullary duodenal Schwannoma on histopathology. Duodenal Schwannomas although rare should be considered in the differential diagnosis of ampullary neoplasms.

Gastric tumors in children: single-center study with emphasis on treatment of repeated recurrence

PURPOSE

Analysis of surgical management and survival of pediatric patients with gastric tumors treated at our institution.

METHODS

A retrospective study of patients with primary gastric tumors treated between 1993 and 2018 was conducted.

RESULTS

Eight patients, five girls and three boys, were diagnosed with gastric tumors at an average age of 10.4 years (1 day-15.4 years). Surgical management included Billroth type I procedure in five and tumor excision in three patients. Histology revealed gastrointestinal stromal tumor (GIST) in four patients and one of each of schwannoma, myofibroblastic tumor, hamartoma and teratoma. Microscopically clear margins were reported in six patients. Repeated local recurrence occurred in three patients (2 × GIST, 1 × myofibroblastic tumors) who consequently underwent three, four and six reoperations. One of these patients had liver metastases, which were managed with ligation of the hepatic arteries. This patient was also diagnosed with a lung hamartoma, which was treated with a lobectomy. Survival rate was 100% with a median follow-up of 8.6 years (7 months-25.5 years).

CONCLUSIONS

Gastric tumors are rare in children and represent a management challenge. Repeated recurrence of GISTs and myofibroblastic tumors remains frequent even after complete resection and may necessitate multiple surgeries, therefore patients require a lifelong follow-up.

Case reports on a gastric mass presenting with regional lymphadenopathy: A differential diagnosis is gastric schwannoma

BACKGROUND

Gastric schwannomas are uncommon among a broad range of possible diagnoses in the work up of a gastric mass. Regional lymphadenopathy associated with gastric schwannoma is an even less common occurrence and one would otherwise suspect a malignant neoplasm.

CASE PRESENTATION

We present two non-consecutive cases from a signle academic center depicting Caucasian females in their 5th and 6th decades of life with gastric schwannoma and adjacent lymphadenopathy. Multiple lymph node excisions were performed without evidence of neoplasia.

DISCUSSION

Lymphadanopathy in the presence of a gastric mass typically represents malignant neoplasm. A less than likely presentation of gastric schwannoma with reactive regional lymph nodes poses a challenge to adequate preoperative diagnosis and increases risk for a more aggressive than necessary surgical approach with lymphadenectomy.

CONCLUSION

While the correlation between gastric schwannoma and lymphadenopathy is uncertain, this ought to be considered. If diagnosis can be confirmed preoperatively, omission of lymphadenectomy is appropriate.

Clinical Characteristics and Surgical Management of Gastrointestinal Schwannomas

Objectives

Schwannomas are tumors arising from Schwan cells of the neural sheath. Gastrointestinal schwannomas (GS) are rare and easily confused with a heterogeneous group of neuroectodermal or mesenchymal neoplasms. The aim of the present study is to analyze the clinicopathological features, surgical management methods, and long-term prognoses of GS patients.

Methods

Between August 2004 and July 2019, 51 patients with GS were treated at the Peking Union Medical College Hospital. The medical records were reviewed retrospectively. A database containing demographic characteristics, clinical symptoms, imaging tests, operation details, pathological results, and prognoses was constructed and analyzed.

Results

GS accounted for 2.0% of all schwannomas. The cohort comprised 19 men (37.3%) and 32 women (62.7%). The mean age was 55.7 ± 11.4 years. The most common symptom was abdominal pain (29.4%). Twenty-seven patients (52.9%) were asymptomatic and diagnosed incidentally. The most common tumor location of GS was the stomach (90.2%). S-100 had the highest positive rate (100%) in immunohistochemical staining. Forty-six patients (90.2%) were followed-up at a mean period of 49.5 ± 41.4 months. Forty-four patients (95.7%) survived without tumor, 1 patient survived with tumor, and 1 patient died. The 5-year cumulative overall survival rate and cumulative disease-free survival rate were 97.5% and 95.2%, respectively.

Conclusion

GS are rare gastrointestinal tumors with favorable prognoses after surgical resection. Stomach is the most common site. Definitive diagnosis is determined by postoperative pathology. S-100 expression has diagnostic significance.

A Serosa-Originated Gastric Stromal Tumor Misdiagnosed by Ultrasonography and Frozen Section Pathology: A Case Report

Gastric gastrointestinal stromal tumor (GIST) is a mesenchymal neoplasm, typically arising from the muscularis propria layer of the stomach wall. Serosa-derived GIST is rarely seen and has not been reported yet. A 49-year-old Chinese female was presented with marked abdominal distension. Ultrasonography revealed a retroperitoneal tumor adjacent to the stomach wall with an intact structure of five echo layers, indicating a non-stomach tumor origin. Preoperative radiological studies suggested tight tumor-stomach adjacency, which was confirmed by intraoperative dissection. Initial frozen section indicated a pathological diagnosis of spindle cell tumor, which turned out to be a gastric GIST originated from the serosa layer of the stomach wall. The current case demonstrates the rare occurrence of serosa-derived GIST. This case also suggests difficulties in preoperative diagnosis of gastric GISTs, especially when uncommon pathological conditions like rare tumor origins were presented.

Clinical characteristics and surgical treatment of schwannomas of the esophagus and stomach: A case series and systematic review

BACKGROUND

Gastrointestinal schwannomas are slow-growing benign mesenchymal neoplasms that originate from Schwann cells of the nerve sheath of Auerbach´s plexus or less frequently from Meissner´s plexus. The main differential diagnosis of gastric schwannomas are the gastrointestinal stromal tumors (GISTs), which are classified by their immunohistochemistry. The treatment of choice for gastric schwannomas is surgery where laparoscopy plays an important role. Wedge resection, subtotal or total gastrectomy can be done. In its counterpart, esophageal schwannomas are benign tumors of the esophagus that are very uncommon since they comprise less than 2% of all esophageal tumors. The main differential diagnosis is the leiomyoma which corresponds to the most common benign esophageal tumor, followed by GIST. The treatment consists on tumoral enucleation or esophagectomy.

AIM

To review the available literature about gastrointestinal schwannomas; especially lesions from de stomach and esophagus, including diagnosis, treatment, and follow up, as well as, reporting our institutional experience.

METHODS

A systematic review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyzes guidelines. The following databases were used for reviewing process: PubMed, Ovid, MEDLINE, and Scopus. Only English language manuscripts were included. All gastrointestinal schwannomas specifically located in the esophagus and stomach were included. Cases that did not report long-term follow-up were excluded.

RESULTS

Gastric localization showed a higher prevalence in both, the literature review and our institution: 94.95% (n = 317) and 83% (n = 5) respectively. With a follow-up with disease-free survival greater than 36 mo in most cases: 62.01% (n = 80) vs 66.66% (n = 4). In both groups, the median size was > 4.1 cm. Surgical treatment is curative in most cases

CONCLUSION

Schwannoma must be taken into account in the differential diagnosis of gastrointestinal mesenchymal tumors. It has a good prognosis, and most are benign. A disease-free survival of more than 36 mo can be achieved by surgery.

Primary adrenal schwannoma: a series of 31 cases emphasizing their clinicopathologic features and favorable prognosis

PURPOSE

Primary adrenal schwannoma (PAS) is a very rare benign tumor, and most of them have been described in case reports. This study aimed to analyze their distinct clinicopathologic features and follow-up data through the largest series yet.

METHODS

Clinicopathologic features of 31 primary adrenal schwannomas were retrospectively studied. Imaging and histologic features were re-evaluated and summarized. Immunohistochemical markers were measured, including S100, SOX10, AE1/AE3, EMA, SMA, Desmin, HMB45, GLUT1, and Ki67. Follow-up of all cases was performed.

RESULTS

All the tumors were clinically misdiagnosed as nonfunctioning adrenal adenoma (NAA; 23/31), aldosterone-producing adenoma/aldosteronoma (APA; 3/31), cortisol-producing adenoma (CPA; 3/31), or pheochromocytoma (PCC; 2/31). Some 87% (27/31) presented with adrenal incidentaloma, and 13% (4/31) had a clinical symptom or unregulated hormone levels. They comprised conventional (19/31), cellular (7/31), plexiform (2/31), ancient (1/31), epithelioid (1/31) and microcystic/reticular variants (1/31) and had various histologic features. Immunohistochemically, all tumors (31/31) were positive for S100 and Sox10, with a low Ki-67 proliferative index. In the long-term follow-up (mean, 53 mo.; median, 56 mo.), none had evidence of recurrence and metastasis. Univariate analysis showed that OS and DFS were not associated with age; sex; tumor side, size, or number; adrenal-related symptoms; gross feature (solid vs. cystic); or any histologic feature (P > 0.9999).

CONCLUSION

PAS is an extremely rare tumor and mostly appears as an incidentaloma. Clinically, it tends to be misdiagnosed as other common adrenal tumors. This tumor has a benign biologic behavior and prognosis, without correlations with clinical or histologic parameters.

Esophageal schwannomas: A rarity beneath benign esophageal tumors a case report

•

Esophageal Schwannoma is a rare tumor with only few cases reported in the literature.

•

In general, Schwanommas are rarely found in the gastrointestinal tract.

•

Esophagic schwanommas is the least common gastrointestinal form of presentation.

•

The knowledge about a new case of esophagic schwanomma, impacts in obtaining more information about the clinical course and surgical treatment of this tumor.

Introduction

Esophageal Schwannoma is a rare tumor that represents the least frequent mesenchymal tumor of the esophagus and represents a condition with only a few cases reported in the literature

Presentation of a case

We report a 40-year-old female with a 5 years history of gastroesophageal reflux, repeated history of pharyngitis, odynophagia that culminated in progressive oropharyngeal dysphagia to solids. A barium esophagogram revealed a filling defect in the superior and middle thirds of the esophagus. Upper gastrointestinal endoscopy showed a smooth elevated lesion in the upper third of the esophagus, impossible to resect by this mean. An open left cervical approach revealed an 80 × 45 × 20 mm large tumor, which was resected.

Discussion

In general, Schwanommas are rarely found in the gastrointestinal tract (GI), while the great majority occur in the stomach, esophagic is the least common GI form of presentation.

Conclusion

The knowledge about a new case, impacts in obtaining more information about the clinical course and surgical treatment of this tumor.

Intestinal Schwannoma: A Clinicopathological, Immunohistochemical, and Prognostic Study of 9 Cases

BACKGROUND

Intestinal schwannoma is a type of intestinal interstitial tumor with a very low incidence. At present, there are few studies on intestinal schwannoma.

METHODS

From January 2010 to January 2018, the patients diagnosed with intestinal schwannoma at the China-Japan Union Hospital of Jilin University were retrospectively reviewed. The patients' clinicopathological features and prognosis were analyzed.

RESULTS

This study enrolled 9 patients with intestinal schwannoma, including 3 males and 6 females. The main symptoms of the patients were abdominal pain and melena. Abdominal computed tomography showed intussusception, slightly high-density shadowing in the intestine, thickening of the intestinal wall, and an intestinal mass. Colonoscopy and endoscopic ultrasonography showed submucosal masses without ulcer formation. Two patients underwent endoscopic biopsy, and the pathological results revealed inflammation and necrosis. One patient had increased neuron-specific enolase (NSE) levels. Immunohistochemical analysis showed that the tumor cells were positive for S-100 and negative for CD117, DOG-1, desmin, and smooth muscle actin. An average of 17 lymph nodes were found around the intestines in 4 patients, all of which demonstrated reactive hyperplasia. No recurrence or metastasis occurred during postoperative follow-up.

CONCLUSIONS

Intestinal schwannoma is a rare tumor, and in our study its incidence was higher in women than in men. The main symptoms were abdominal pain and melena. Preoperative increases in NSE levels might contribute to a diagnosis. Complete surgical resection with free negative margins is the standard treatment for benign schwannoma. There was no recurrence or metastasis after complete surgical resection, suggesting that follow-up may not be required.

Schwannoma in the ascending colon, a rare finding on surveillance colonoscopy

Schwannomas are peripheral nerve sheath tumours that can present as a rare tumour of GI tract, and even more uncommonly within the colon. We present a case of colonic schwannoma in an asymptomatic patient identified on surveillance colonoscopy. The tumour is of mesenchymal origin and is often challenging to diagnose prior to surgical resection. Endoscopy usually fails to provide adequate sample and diagnosis is usually confirmed on immunohistochemistry.

Gut-associated lymphoid tissue or so-called “dome” carcinoma of the colon: Review

AIM

To present a comprehensive review of the etiology, clinical features, macroscopic and pathological findings, and clinical significance of Gut-associated lymphoid tissue or “dome” carcinoma of the colon.

METHODS

The English language medical literature on gut- or gastrointestinal-associated lymphoid tissue (GALT) or “dome” carcinoma of the colon was searched and appraised.

RESULTS

GALT/dome-type carcinomas of the colon are thought to arise from the M-cells of the lymphoglandular complex of the intestine. They are typically asymptomatic and have a characteristic endoscopic plaque- or “dome”-like appearance. Although the histology of GALT/dome-type carcinomas displays some variability, they are characterized by submucosal localization, a prominent lymphoid infiltrate with germinal center formation, tumor-infiltrating lymphocytes, absence of desmoplasia, and dilated glands lined by columnar epithelial cells with bland nuclear features and cytoplasmic eosinophilia. None of the patients reported in the literature with follow-up have developed metastatic disease or local recurrence.

CONCLUSION

Increased awareness amongst histopathologists of this variant of colorectal adenocarcinoma is likely to lead to the recognition of more cases.

Esophageal schwannoma: Case report and epidemiological, clinical, surgical and immunopathological analysis

INTRODUCTION

Schwannoma is a tumor of the peripheral nervous system originated in the Schwann cells of the neural sheath.

PRESENTATION OF CASE

A 43-years-old male complained of odynophagia, dysphagia and hemoptysis. The upper gastrointestinal endoscopy showed a smooth elevated lesion, 20 cm from the incisor teeth, occupying the entire lumen of the esophagus. The chest computed tomography (CT) scan showed a lesion of 7 cm and superior mediastinal, lower paraesophageal and cardiac enlarged lymph nodes. A posterolateral thoracotomy was performed with total esophagectomy without intraoperative complications. The anatomopathological analysis revealed fusocellular mesenchymal neoplasia of low malignancy potential. The immunohistochemical study showed positivity for S-100 protein and KI67 antibodies and absence of staining for CD117, CD34, ALK protein, SMA and Desmin. Thus, the morphological and immunohistochemical findings pointed to the diagnosis of esophageal Schwannoma.

DISCUSSION

Although rare and indolent, Schwannoma occurs in the peripheral nervous system, being uncommon in the esophagus.

CONCLUSION

The immunohistochemical study is essential for the diagnosis, which is based on the positivity for S-100 protein and absence of staining for CD34 and CD117.

Case of colonic mucosal Schwann cell hamartoma and review of literature on unusual colonic polyps

Mucosal Schwann cell hamartomas (MSCH) are benign mesenchymal tumours rarely seen in the gastrointestinal tract. They occasionally present as incidental sessile polyps during colonoscopy. A 55-year-old asymptomatic female patient with a medical history of multiple sclerosis presented for a screening colonoscopy. A 5 mm low-risk tubular adenoma was noted in the caecum, and a second 5 mm polyp was found in the ascending colon. Histopathology of the ascending colon polyp showed proliferation of spindle cells without ganglion cells in the lamina propria. Immunohistochemical findings are compatible with an MSCH. Surveillance colonoscopy was scheduled in 5 years based on the presence of a single low-risk tubular adenoma.

Gastrointestinal schwannomas: a rare but important differential diagnosis of mesenchymal tumors of gastrointestinal tract

BACKGROUND

Schwannomas of gastrointestinal tract are rare, mostly benign and notably different neoplasms from conventional schwannomas that arise in soft tissue or the central nervous system. These tumors are of clinical importance since they should always be considered in the differential diagnosis of submucosal lesions of gastrointestinal tract.

METHODS

Seven patients with a pathologically proven gastrointestinal schwannoma were identified in our series of mesenchymal tumors and reviewed retrospectively. Clinicopathological and immunohistochemical parameters along with the follow-up results were analysed.

RESULTS

The series included two males and five females, with a mean age 69 years (range, 39-81). Most patients were asymptomatic on presentation, except for two patients with abdominal pain. In the other cases (n = 5), the tumor was an incidental finding during other medical, imaging or surgical procedures. The tumors were located in the stomach (n = 4) and in the small intestine (n = 3) with an average size of 29 mm (range, 12-70). A preoperative diagnosis was achieved only in one case with a CT-guided core biopsy. Otherwise the clinical, intraoperative, endoscopic or radiological findings were unspecific. Patients with gastric tumor underwent either laparoscopic (n = 2) or open (n = 2) gastric wedge resection of the tumor; in the cases of intestinal tumor (n = 3) a segmentectomy was performed. Pathological examination revealed solid homogenous tumors, which were highly cellular and composed of spindle cells with positive staining for S100 protein, and confirmed the diagnosis of schwannoma. All tumors were negative for c-Kit, smooth muscle actin, desmin and DOG-1 and showed very low proliferation index. There were negative resection margins and no malignant variants were recognized. At an average follow-up of 60 months (range, 24-185) all patients were free of disease with no signs of recurrence or metastases and acceptable gastrointestinal function.

CONCLUSIONS

Schwannomas are rare, slow-growing and mostly asymptomatic gastrointestinal mesenchymal tumors. They are difficult to be diagnosed preoperatively as endoscopic and radiological findings are nonspecific but histological and immunohistochemical features are of paramount importance to differentiate between benign and malignant schwannomas, or other spindle cell sarcomas. The treatment of choice is complete surgical excision without a conclusive preoperative diagnosis, and the long-term outcome is excellent as these lesions are mostly benign.

Endoscopic ultrasound FNA: An illustrated review of spindle cell neoplasms of the upper gastrointestinal tract including a novel case of gastric plexiform fibromyxoma

Plexiform fibromyxoma (PF) is a recently-described and rare mesenchymal neoplasm of the gastric wall. A few small case series reports of this spindle cell entity exist in the surgical pathology literature, but to our knowledge no prior endoscopic ultrasound guided fine needle aspiration cytology examples have been reported. In clinical practice, mural gastrointestinal (GI) lesions are often initially evaluated by endoscopic ultrasound guided (EUS) fine needle aspiration (FNA). In addition, newer EUS fine needle biopsy techniques also allow for reliable retrieval of core tissue samples with intact cellular architecture, making EUS histopathologic analyses possible. We report a combined EUS FNA and core biopsy case of PF and correlate the findings with imaging results. The cytomorphology of PF is described and illustrated, and important entities in the differential diagnosis of upper GI spindle cell lesions (including GI stromal tumor, leiomyoma, schwannoma, carcinoid tumor, desmoid-type fibromatosis, and inflammatory fibroid polyp) are reviewed. Illustrated examples of relevant cytomorphologic, cell block histomorphologic and immunohistochemical characteristics are emphasized.

A Rare Duodenal Subepithelial Tumor: Duodenal Schwannoma

Schwannomas are uncommon neoplasms that arise from Schwann cells of the neural sheath. Gastrointestinal schwannomas are rare among mesenchymal tumors of the gastrointestinal tract, and only a few cases have been reported to date. Duodenal schwannomas are usually discovered incidentally and achieving a preoperative diagnosis is difficult. Schwannomas can be distinguished from other subepithelial tumors on endoscopic ultrasonography; however, any typical endosonographic features of duodenal schwannomas have not been reported due to the rarity of these tumors. Immunohistochemistry is essential to distinguish schwannomas from gastrointestinal stromal tumors and leiomyomas. We report a case of duodenal schwannoma found incidentally during a health check-up endoscopy. On endoscopic ultrasonography, this tumor was suspected as a gastrointestinal stromal tumor; therefore, the patient underwent laparoscopic wedge resection of the tumor. Histopathology and immunohistochemistry confirmed that the duodenal lesion was a benign schwannoma.

99m-Technetium Sestamibi Uptake in a Gastric Schwannoma

We report the case of a 74-year-old woman with primary hyperparathyroidism who underwent 99m-technetium-sestamibi single photon emission computed tomography-computed tomography for preoperative localization of parathyroid adenoma. Unexpected focal sestamibi uptake was observed at a 5 cm submucosal tumor arising from the greater curve of the stomach. The patient underwent partial gastrectomy and the histological and immunohistochemical findings were consistent with the diagnosis of gastric schwannoma.

Differentiation between gastrointestinal schwannomas and gastrointestinal stromal tumors by computed tomography

The aim of the present study was to identify computed tomography (CT) features to assist in differentiating gastrointestinal schwannomas from gastrointestinal stromal tumors (GISTs). CT images of gastrointestinal schwannomas (n=15) and GISTs (n=50) were analyzed. The absolute CT values of tumor/aorta during plain scan/arterial phase/venous phase were recorded as tumor plain scan (Tp)/aorta plain scan (Ap), tumor arterial phase (Ta)/aorta arterial phase (Aa) and tumor venous phase (Tv)/aorta venous phase (Av), respectively, and normalized CT values of the three phases were calculated as Sp=Tp/Ap, Sa=Ta/Aa and Sv=Tv/Av, respectively. The difference in tumor CT value between arterial and venous phases was calculated and recorded as Tv-a. CT data including tumor size, contour, margin, growth pattern, presence of calcification, cystic change, hemorrhage, ulceration, perilesional lymph nodes (PLNs), local invasion to surrounding structures, metastasis, ascites, vasculatures, enhancement pattern/degree, Tp/Ta/Tv and Sp/Sa/Sv were evaluated for each patient. Receiver operating characteristic (ROC) curve analysis was used to assess the ability of the CT data to differentiate gastrointestinal schwannomas from GISTs. Compared with GISTs, gastrointestinal schwannomas more frequently demonstrated round contouring, relatively smaller tumor size, a homogeneous enhancement pattern, with the presence of PLNs and a higher level of vasculature (P<0.05), whilst the presence of cystic changes were more common in GISTs compared with gastrointestinal schwannomas (P<0.05). The Sa, Ta and Tv-a of gastrointestinal schwannomas were less compared with those of GISTs (P<0.05). The difference in margin, growth pattern, intra-tumoral calcifications and hemorrhage were insignificant (P>0.05). ROC analysis indicated that tumor size, cystic change, the presence of PLNs, tumor enhancement pattern and Sa demonstrated improved diagnostic potential compared with others [area under the curve (AUC) >0.7], amongst which cystic change demonstrated the best diagnostic ability (AUC=0.82). Size exhibited the highest sensitivity, 90%, and cystic change, Sa exhibited the best specificity, 87%. Quantitative analysis indicated that certain features aided the differentiation between gastrointestinal schwannomas and GISTs using CT imaging.

Endoscopic ultrasonographic characteristics of gastric schwannoma distinguished from gastrointestinal stromal tumor

BACKGROUND/AIMS

Gastric schwannoma (GS), a rare neurogenic mesenchymal tumor, is usually benign, slow-growing, and asymptomatic. However, GS is often misdiagnosed as gastrointestinal stromal tumors (GIST) on endoscopic and radiological examinations. The purpose of this study was to evaluate EUS characteristics of GS distinguished from GIST.

METHODS

A total of 119 gastric subepithelial lesions, including 31 GSs and 88 GISTs, who were histologically identified and underwent EUS, were enrolled in this study. We evaluated the EUS characteristics, including location, size, gross morphology, mucosal lesion, layer of origin, border, echogenic pattern, marginal halo, and presence of an internal echoic lesion by retrospective review of the medical records.

RESULTS

GS patients comprised nine males and 22 females, indicating female predominance. In the gross morphology according to Yamada's classification, type I was predominant in GS and type III was predominant in GIST. In location, GSs were predominantly located in the gastric body and GISTs were predominantly located in the cardia or fundus. The frequency of 4th layer origin and isoechogenicity as compared to the echogenicity of proper muscle layer was significantly more common in GS than GIST. Although not statistically significant, marginal halo was more frequent in GS than GIST. The presence of an internal echoic lesion was significantly more common in GIST than GS.

CONCLUSIONS

The EUS characteristics, including tumor location, gross morphology, layer of origin, echogenicity in comparison with the normal muscle layer, and presence of an internal echoic lesion may be useful in distinguishing between GS and GIST.

Endoscopic ultrasound with tissue sampling is accurate in the diagnosis and subclassification of gastrointestinal spindle cell neoplasms

Background and Objectives:

Mesenchymal (spindle cell) neoplasms (SCN) of the gastrointestinal (GI) tract are an important subtype of subepithelial lesions that need subclassification to assess their malignant potential. Reported success rates of accurate subclassification with endoscopic ultrasound (EUS)-guided biopsies are variable. Our goal was to analyze our experience using EUS-guided TruCut biopsy (EUS-TCB) in the majority of patients.

Methods:

Retrospective analysis in patients who underwent EUS with biopsies for suspected SCN at our tertiary referral center between 2004 and 2013.

Results:

A total of 146 patients with suspected SCN underwent EUS with tissue acquisition. Thirteen patients were excluded from analysis because tissue acquisition established a definite diagnosis other than SCN. In the remaining 133 patients, tissue acquisition was diagnostic of SCN in 118 (88.7%) and nondiagnostic in 15 (11.3%). Subclassification based on immunohistochemistry (IHC) was possible in 109 of the 133 cases (81.9%). The final diagnosis was GI stromal tumor in 64, leiomyoma in 39, and schwannoma in 6 cases. The percentage of patients who were subclassified by the various EUS-guided techniques together was 72.18%, and the percentage of patients who were subclassified specifically with EUS-TCB was 61.65%. Tissue specimens that enabled a specific diagnosis based on histological or cytological characteristics in conjunctions with IHC were obtained with EUS core biopsy in 83 (TCB in 82 and ProCore needle biopsy in 1), fine-needle aspiration in 13, mucosal resection in 10, and forceps biopsies (bite-on-bite) in 3 cases.

Conclusion:

EUS with endoscopic tissue acquisition is accurate in the diagnosis and subclassification of SCN. In experienced hands, the EUS-TruCut needle is a valuable tool with a high success rate for this indication.

CT Features of Colorectal Schwannomas: Differentiation from Gastrointestinal Stromal Tumors

Purpose

To find differential CT features of colorectal schwannomas from gastrointestinal stromal tumors (GISTs).

Materials and Methods

CT features of 13 pathologically proven colorectal schwannomas and 21 GISTs were retrospectively reviewed. The following CT items were analyzed: size, longitudinal and transverse location, shape, margin, homogeneity, necrosis, surface ulceration, calcification, degree of attenuation, the presence of enlarged lymph node (LN), and metastasis. Among the features, significant variables were evaluated using univariate statistical tests. The optimal cut-off point of tumor size was obtained by ROC analysis. Binary logistic regression analysis was used to find the most independent CT variables.

Results

Small size, non-rectum location, smooth margin, homogeneous high attenuation without necrosis, and the presence of enlarged LNs were found to be significant variables to differentiate schwannomas from GISTs (P<0.05). The optimized cut-off point for tumor size in distinguishing GISTs from schwannomas was 3.9 cm (AUC = 0.808, sensitivity = 66.7%, specificity = 92.3%, P<0.0001). Binary regression analysis revealed that only non-rectum location remained independent predictor for schwannomas differentiated from GISTs (odds ratio = 31.667, P = 0.001).

Conclusion

Colorectal schwannomas usually located in non-rectum and appear as small subepithelial nodules showing homogeneous high attenuation and smooth margin. Schwannomas exclusively accompany with enlarged LNs.

Colonic Schwannoma: A Case Study and Literature Review of a Rare Entity and Diagnostic Dilemma

An asymptomatic 73-year-old woman was found to have a submucosal mass in the descending colon on routine colonoscopy. A CT scan revealed a 31 X 28 X 31 mm lesion in the same location. Previous biopsy proved to be nondiagnostic, and the patient underwent a laparoscopic descending colon resection. Histologic evaluation of the tumor revealed a low grade spindle cell neoplasm with strong, diffuse positivity for S-100 protein by immunohistochemistry, leading to the diagnosis of schwannoma. A review of the literature revealed intestinal schwannoma to be a rare disease entity, with only about 50 cases previously reported.

Endosonographic Features of Gastric Schwannoma: A Single Center Experience

BACKGROUND/AIMS

Gastric schwannomas are rare benign mesenchymal tumors that are difficult to differentiate from other mesenchymal tumors with malignant potential, such as gastrointestinal stromal tumors. This study aimed to evaluate the characteristic findings of gastric schwannomas via endoscopic ultrasonography (EUS).

METHODS

We retrospectively reviewed the EUS findings of 27 gastric schwannoma cases that underwent surgical excision at Pusan National University Hospital during 2007 to 2014.

RESULTS

Gastric schwannomas were mainly located in the middle third of the stomach with a mean tumor size of 32 mm. All lesions exhibited hypoechoic echogenicity, and 24 lesions (88.9%) exhibited heterogeneous echogenicity. Seventeen lesions (63.0%) exhibited decreased echogenicity compared to the normal proper muscle layer. Distinct borders were observed in 24 lesions (88.9%), lobulated margins were observed in six lesions (22.2%), and marginal haloes were observed in 24 lesions (88.9%). Hyperechogenic spots were observed in 21 lesions (77.8%), calcifications were observed in one lesion (3.7%), and cystic changes were observed in two lesions (7.4%).

CONCLUSIONS

During EUS, gastric schwannomas appear as heterogeneously hypoechoic lesions with decreased echogenicity compared to the normal proper muscle layer. These features may be helpful for differentiating gastric schwannomas from other mesenchymal tumors.

Clinical, Morphologic, and Pathologic Features Associated With Increased FDG Uptake in Schwannoma

OBJECTIVE

The objective of this study was to investigate the clinical, morphologic, and pathologic features associated with increased ¹⁸F-FDG uptake in benign schwannomas.

MATERIALS AND METHODS

Twenty-two schwannomas in 22 patients (age range, 25-81 years) who had FDG PET or PET/CT scans and subsequently underwent surgical re-section were retrospectively analyzed. The maximum standardized uptake value (SUV_max) was compared with patient age, sex, tumor location (gastrointestinal vs nongastrointestinal origin), tumor size, gross appearance, intratumoral cellularity, intratumoral infiltration of inflammatory cells, presence of peritumoral lymphoid cuffs, and expression status of glucose transporters 1 and 3 on tumor cells.

RESULTS

The SUV_max of schwannomas ranged from 1.5 to 17.3 (median, 3.7). Significantly higher SUV_max was observed in gastrointestinal schwannomas (n = 4) compared with nongastrointestinal schwannomas (n = 18, p = 0.007) and in schwannomas with peritumoral lymphoid cuffs (n = 5) compared with those without peritumoral lymphoid cuffs (n = 17, p = 0.001). A significant correlation was seen between tumor location and the presence of peritumoral lymphoid cuffs (p < 0.001). Age, sex, tumor size, gross appearance, intratumoral cellularity, intratumoral inflammatory cell infiltration, and expression status of glucose transporters 1 and 3 on tumor cells had no significant correlation with SUV_max.

CONCLUSION

Gastrointestinal schwannomas and schwannomas with peritumoral lymphoid cuffs may be associated with elevated FDG uptake. Knowledge of the features of schwannomas associated with increased uptake may be helpful to avoid misinterpretation of benign schwannomas as malignancy.

Gastrointestinal tract spindle cell tumors with interstitial cells of Cajal: Prevalence excluding gastrointestinal stromal tumors

Leiomyomas and schwannomas of the gastrointestinal tract (GIT) are mainly comprised of spindle-shaped tumor cells and should always be differentiated from gastrointestinal stromal tumors (GISTs). Mast/stem cell growth factor receptor Kit (KIT) and discovered on GIST-1 (DOG1) are well-known diagnostic markers for the detection of a GIST by immunohistochemical staining. The aim of the present study was to assess the prevalence and significance of spindle cell tumors of the GIT with KIT- or DOG1-positive spindle-shaped cells, presumed to be interstitial cells of Cajal (ICCs), other than GISTs. A total of 71 leiomyomas and 35 schwannomas were examined and clinicopathological information was obtained. KIT and DOG1 immunostaining was performed to determine the proportions of positive cells. Mutation screening of KIT exons 9, 11, 13 and 17, and platelet-derived growth factor receptor α (PDGFRA) exons 12 and 18 was performed in cases with a relatively high proportion of either KIT- or DOG1-positive cells. The frequency of leiomyomas and schwannomas with KIT- and DOG1-positive ICCs was 35.2% (25/71 cases) and 5.7% (2/35 cases), respectively. Among the esophageal leiomyomas with KIT- and DOG-positive ICCs (14/25; 56.0%), 5 leiomyomas involved the muscularis mucosa and 9 leiomyomas involved the muscularis propria. All gastric leiomyomas with KIT- and DOG1-positive ICCs (11/25; 44%) involved the muscularis propria. All schwannomas with an increased proportion of KIT- or DOG1-positive ICCs were of gastric origin. No KIT or PDGFRA mutations were detected in 7 leiomyomas and 2 schwannomas. In conclusion, the majority of leiomyomas and the minority of schwannomas in the GIT had a significant portion of KIT- and DOG1-positive cells. All of the tumors were located in the upper GIT, and could be present in the muscularis propria or muscularis mucosa. The tumors represented a non-neoplastic proliferation of KIT- and DOG1-positive cells in the GIT. Careful evaluation of KIT- or DOG1-positive cells in spindle cell tumors of the GIT can assist in forming the correct diagnosis by differentiation from a GIST.